Electric meter.



T.,.DUN0,AN. A ELECTRIC METER. APPLICATION FILED PEB.1.,1909.

PatentedJuly 27, 1909.

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ELECTRIC METER.

APPLIUATION FILED FEB. 1,1909.

929, 1 23. Patented July 27,- 1909.

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UNITED sTATEsv PATENT oEEroE.

THOMAS DUNCAN, OF LA FAYETTE, INDIANA, ASSIGNOR TO DUNCAN ELECTRIC MANUFAC- TURING COMPANY, OF LA FAYETTE, INDIANA, A CORPORATION OF INDIANA.

ELECTRIC METER.

Specification of Letters Patent.

Patented July 27, 1909.

Application filed February 1, 1909. Serial N o. 475,518.

To all 'whom 'it may concern:

Be it known that I, THOMAS DUNCAN, citizen of the United States, residing at La Fayette, in the county of Tippecanoe and State of Indiana, have invented a certain new and useful Improvement in Electric Meters, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to inte rating electric wattmeters and is of particu ar service in connection with such meters that are adapt-y ed to the carriage of large currents.

The meter of my invention includesa simple means for Calibrating or checking up the accuracy thereof in a short space of time without requiring the use of expensive ammeters and a knowledge of electrical measurements.

It is customary to have the switch-boards of electric lighting and power plants equipped with heavy meters that measure the energy given out from the dynamos, these meters frequently serving to enable the management to observe from time to time just what the total consum tion of current in an electric plant is and a so the rate of consumption from day to day or week to week, as the case may be. Usually electric lighting and power plants are not equipped with testing instruments large enough to check up these large meters. Let it be supposed that a switchboard is equipped with a five thousand ampere meter whose accuracy is to be checked nlp. The one who is to do the checking usua y lacks the large ampere ammeter for the purpose of checking, though he may be in Ipssession of the necessary volt meter.

oreover, even though the necessary ammeter were at hand, some knowledge of the electrical art would be requiredfor the checking operation.

In accordance with the preferred embodiment of my invention, I employ a supplemental pressure coil which I provide preferably to the exclusion of the main current or series coils, whereby a field is produced which cooperates with the normal pressure circuit of the meter to secure movement of the rotating element of the meter, that should be at a predetermined rate if the meter is in good condition, the voltage with which the meter is impressed being brought to a predetermined value for the purpose.

My invention finds a very important embodiment in direct current watt meters. Where these meters are provided with friction compensating coils, I cause these coils to coperate with the additional coils that I have provided for testingk purposes, to eect the desired movement of the meters when being tested, the armature of each meter being disposed between a starting coil and the testing coil. Where the torque or starting coil is not caused to assist the test coil, said test coil is preferably Vsubdivided into at least two parts, between which the moving element is disposed. Y

When the test is to be main current or series coil should preferably be separated from the load, so that the field that cooperates with the main pressure :field for testing purposes is sure to be maintained constant during the test, which-would not be the case if a load, however slight, were to be permitted upon the system during the test.

I will eXp ain my invention more fully by reference to the accompanyingV drawings, showing some embodiments thereof.

In the drawings-Figure 1 illustrates an integrating watt meter having a single armature, the circuit connections of the various parts of the meter being diagrammatically indicated. Fig. 2 illustrates an astatic integrating watt meter having two armatures, the circuit connections of the various arts of the meter being diagrammaticall illustrated. Fig. 3 is a diagrammatic i lustration of another adaptation of my invention to astatic integrating watt meters. Fig. 4 is a diagrammatic illustration of another embodiment of my invention.

Like parts are indicated by similar characters of reference throughout the different figures.

In each of the iigures I have illustrated a source of suitable current 1, in this instance a source of direct current, connected in circuit with supply mains 2, that are extended to the translating devices 3, that constitute the load supplied with current from the generator l, a manually controlled switch 4 having members that are serially included in the sides 2 of the circuit, said switch serving to associate the load with and separate it from said source of current. Each of the meters illustrated includes a current or series field conductor element 5, which in power meters is large in size, and a pressure field producing roceeded with, the

element in the form of a commutated armature 6, to which, however, l do not wish to be limited., this armature being divided into vtwo arts in the embodiment of Vthe invention illustrated in Figs. 2 and 3, in accordance with well known practice, the portions of the armature illustrated in 2 and 3 being designated as 61. Each of the meters shown is provided with a commutator 7 against which commutator brushes 8 rest, one commutator brush being connected with one main of the system and the companion commutator brush being connected with the other main of the system, whereby the armature coils are subjected to the )ressune impressed upon the system, the fie d produced by an active armature winding and the current field producing portion of the meter effecting movement of the rotating element of the meter proportional to the energy or wattage of the system.

The counting train 9 (Figs. 1, 2 and 3) may be suitably driven by the rotating element of the meter, the motion of said rotating element being suitably retarded as by means of a damping disk 10 arranged within the fields of permanent magnets 11 (Figs. 1, 2 and 3).

Referring now more particularly to Fig. 1, themeter there shown is provided with the usual form of friction compensating or torque coil 12, that is included in the'same bridge circuit across the mains 2, which includes the brushes 8 and the extraneous resistance 13, according to common practice; The parts thus far described in connection with the y drawings constitute meters as they are adapted for normal service. The parts which l supply to the meter illustrated in Fig. 1 are the testing coil 14, the extraneous resistance 15, and a manually controlled switching device 16, there lfeing suitaole connections whereby the switching device 16 may include the test coil 14 in bridge of the mains 2 or exclude said test coil from circuit, said test coil being included in circuit when the meter is to be tested. The manually controlled switching mechanism 4, 16 is provided at the power station and is operated when the meter is to he tested, to dissociate the load 3 from the mains 2, thereby to open circuit through the field portion 5 and to close circuit through that bridge conductor which includes the test coil 14 and the resistance 15, whereby the field produced by `the torque coil 12, which never should be sufficient to cause the meter to operate on no load, is supplemented to a predetermined extent by the test coil 14, so that when the voltage impressed upon the system is brought vto the requisite value, there should be a predetermined rate of movement of the armature, if the meter is in good working order, there being preferably suliicient resistance in the bridge circuit containing the test coil ito make the meter-run sumciently slow, in

order that the test may be readily made. If the meter, when being tested, does not run at a suitable speed, simple adjustments Aknown to those at all familiar with meter have become slightly demagnetized from' any cause, the speed of the meter would be more than ten revolutions, whereupon the attendant, in a very simple way, should adr `iust the position of the retarding magnets 11, so as to increase the retardation and bring the speed to ten revolutions. When this is accomplished, the meter is correct, the correction not requiring any professional knowledge nor the use of high-priced instruments, n or the sending of an expert to the plant. After the test has been concluded, the switch 4 should be closed and the switch 16 should be opened, thereby to restore the normal circuit relation of the meter with the system. Y

rlhus my simple invention is productive of many advantages which will be readily apparent to those skilled in the art and which l do not believe have hitherto been secured.

While l have supplied the testing coil 14 with current flowing in a second bridge conductor, as illustrated in Fig. 1, I do not wish to he limited to the means whereby said testing coil is supplied with energizing current for testing purposes. The presence of the switch 4 is desirable inasmuch as the test may then be made at any time and inasmuch as assurance is afforded respecting the absence of any load, however slight, and although.` this is my preferred practice, l do not wish to he limited in all emlodiments of the invention to the employment of the switch 4.

The apparatus illustrated in Fig. 2, in so far as the testing facilities are concerned, is generally similar to the apparatus illustrated in Fig. 1. The series or current field portion 5 is differently shaped, the meter illustrated being an astatic meter, the armature being divided into two parts 61 having a common commutator 7.

In the form of the invention shown in 2, the starting or torque coil 12 is in association with one armature section 61 and the testing coil 14 is divided into two parte be tween which the companion armature section 61 is disposed. In the form of the invention illustrated in Fig. 2, the starting, friction or torque coil 12 also aids the test coil 14 in its function. In the system of Fig. 2

conductor which is separate from the bridge conductor which includes the armature of the meter. In testing the instrument of the system of Fig. 2, the same operations are preferably performed as in the case of the equipment shown in Fig. 1.

The type of meter illustrated in Fig. 3 is generally similar to the type of meter illustrated in Fig. 2. In Fig. 3 the friction compensating or torque coil 12 is subdivided into two parts that are located in association with the u per armature section 61 while the testing coi which is divided into two arts 14,v is shown in association with the ower armature section 61. The switch 16, in the appara-tus of Fig. 3, unlike the switch of Figs. 1 and 2, is always in circuit, there being but one bridge connection with each mainl` said switch being in permanent connection with the lower main, and in one position serving` to include the torque coil 12 only in circuit, together with suitable external resistance indicated at 17, and in the other position, to include the test coils 1.4 in circuit and in series with the torque coils 12 and a reduced portion of the resistance 17, suflicient resistance at 17 being excluded from the testing coil circuit to equal the resistance of the inserted test coil. By the arrangement shown in Fig. 3, there is but one bridge circuit and the resistance thereof is maintained constant irrespective of the presence or the absence of the test coils in the circuit arrangement.

In the system shown in Fig. 4, the armature is not subdivided as in the systems of Figs. 2 and 3, the current field winding or circuit portion having a shape which is different from that illustrated in Figs. 2 and 3. The circuit relations of the single testing coil shown in Fig. 4 and the single compensating coil are similar to the circuit relations of the double compensating coil and the double testing coil shown in Fig. 8, and I will not specifically describe the circuits of Fig. 4.

The preferred embodiment of the invention is illustrated in Fig. 4, in that the same number of milli-amperes of current are caused to flow through a single shunt or bridge circuit Whether the testing coil is present or absent, so that most extreme accuracy is simply and absolutely assured in the testing operation. In the preferred embodiment of the invention, the test coil is not subdivided and is of such a structural shape that it may readily be included within the series field coil or portion, so that there is no materially noticeable change in the physical appearance or make-up of the completed instrument.

In Figs. 2 and 3 each of the coils 12 and each of the coils 14 are supposed to occupy a position, in practice, ninety degrees from the position in which they are illustrated, the coils being shown in their present positions in Figs. 2 and 3 for the sake of clearness.

Vv hile I have herein shown and particureadily be made without departing from the spirit of my invention.

Having thus described my invention, I claim as new and desire to secure by Letters Patent the following l. In a system of electrical distribution, the combination with an integrating watt meter in operative association with a distribution circuit of the system and capable of measuring the energy supplied by said circuit, of a supplemental pressure field winding supplied in addition to those parts of the meter structure that constitute it a meter adapted to measure the energy supplied by said circuit and normally out of coperative relation with the meter structure to permit of the proper normal operation of the meter and serving, in coperation with thev armature of the meter, to operate the meter to test the meter speed, and manually ycontrolled switching mechanism for bringing said supplemental pressure field winding into and out of operating relation with the meter armature f 2. A system of electrical distribution including an integrating watt meter in operative association witha distribution circuit of the system and capable of measuring the energy supplied by said circuit, the meter bein supplied with a su plemental pressure lie d winding normally orming no field coil portion of the meter, and manually controlled means for bringing said supplemental pressure field Winding into and out of operating relation with the meter armature, in order that the meter may be operated to test its speed. r

3. In a system of electrical distribution, the combination with an integrating watt meter in operative association with a distribution circuit of the system and capable of measuring the energy supplied by said circuit, of a supplemental test field winding supplied in addition to those parts of the meter structure that constitute it a meter adapted to measure the energy supplied by said circuit and normally out of coperative relation with the meter structure to permit of the proper normal operation of the meter and serving, in coperation with the armature of themeter, to operate the meter to test the meter speed, and manually controlled switching mechanism for bringing said supplemental field winding into and out of operating relation with the meter armature.

4. A system of electrical distribution including an integrating watt meter in operative association with a distribution circuit of the system and capable of measuring the energy supplied by said circuit, the meter being supplied With a supplemental iield winding normally forming no field coil portion of the my nameV this 28th day of January A. D., meter, and manually controlled means for 1909. bringing said supplemental field Winding into and out of operating relation With the meter 'lHOMAS DUNCAN' 5 armature, in order that the meter may be op- Witnesses:

erated to test its speed. LEON G. STROH,

In Witness whereof, I hereunto subscribe C. L. CRAGG. 

